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Discussion Starter · #1 · (Edited)
Since almost all of the forums concentrating on DIY boatbuilding have been 'converted' or overwhelmed with Porn, Spam, 'crap', etc. can anyone recommend a good website/forum that still concentrates on boatbuilding, especially ultra-lightweight hulls, etc. using composite and cored composite structure.

Im interested in building an ultra-light weight ~17-18ft. cored lapstrake Whitehall/Wherry 'pulling boat', particularly using an alternative to heavy "C-flex" and either balsa or klegecell as the core, and dont want to go through the ultimate agony of building a 'female' mold for the lay up. I think this can be done faster / easier using a male plug mold, etc. etc.

Any direct advice for locating a non-trashed 'boat building in composites' forum, etc. would be very much appreciated.
 

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If the core material is not too floppy, just build the hull over bulkheads and glass the outside to perfection and flip to do the inside. Custom gunnels for sure. See Whitehall Reproductions in Victoria BC
 

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Over Hill Sailing Club
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I don't know of any particular source of information for this kind of project although I have often contemplated building a small boat this way. I guess just slogging through a lot of forums is probably all you can do. I looked for info. on lightweight, foam core construction when building a little pram to use as a dink but wound up using stitch and glue. Using foam core has a lot of pitfalls such as air expansion/delamination, adhesion problems, and water saturation. I think a lot of the building going on is largely experimental. Try surfboard building sites as well, such as Greenlight Supply. They have been dealing with glass and foam as long as anyone. I just finished a paddleboard using epoxy and EPS foam, complete with Goretex venting. It has developed some expansion-induced delamination in the hot Florida sun. So there is more to this than meets the eye.
 

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Since almost all of the forums concentrating on DIY boatbuilding have been 'converted' can anyone recommend a good website/forum that still concentrates on boatbuilding, especially ultra-lightweight hulls, etc. using composite and cored composite structure.

Im interested in building an ultra-light weight ~17-18ft. cored lapstrake Whitehall/Wherry 'pulling boat', particularly using an alternative to heavy "C-flex" and either balsa or klegecell as the core, and dont want to go through the ultimate agony of building a 'female' mold for the lay up.
Have you attended this event? Good sources...

CBMM Mid Atlantic Small Craft Festival
 

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I have watched someone build a nice pulling dinghy using the method described below.

Set up a transom and midships frame plus a stem on a flat surface. Builder used reclaimed sheetrock plus some timber reclaimed from a pallet.

Using 1 inch wide strips of 1/8th timber he 'planked' the hull. There was no real attempt made to do this with out gaps although there was some shaving down on width at the stem.

Next step was to stretch nylon over the hull. Recycled torn spinnaker material was used.

Gelcoat was rolled on followed by layers of mat the more resin with color to finish. Once cured the interior frame and nylon was removed and a timber gunnel plus seat added. The boat was used a pulling tender for years and was very easy to row.

Although no foam was used I think it would be possible to build a composite hull this way. Maybe using epoxy rather than polyester and urethane foam.

I have sliced 1/4 inch 'planks' of foam of 6 in thick piece of foam using a hot wire cutter
 

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All Rats seem to agree here. Wooden Boat forum is by far the best place for all things boat building. You will not find a more knowledgeable group of sailors and builders anywhere on the internet. They will enlighten you on your choices. Cheers. Justin
 

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Discussion Starter · #12 ·
Thanks for all the hints and advice, much appreciated and all 'food for thought'.
I already have a design in mind such as the heavyweight Wherry from John Gardner's textbook ... easy to loft from the detailed offsets already in existence (Mystic).

The execution in ultra-light composites is the 'grey area' in that there is insufficient historical scantling/strength performance data whether by molding a complete lapstraked-looking (an absolute requirement) hull versus the stress considerations of the resin rich areas that joining such strakes as individual strakes as when building in wood ..... or lay-up the strake cores over a 'male plug' together & simultaneously. Couple that with a desire for a monocoque hull (little to no ribs/knees and other internal supports, etc.), daggerboard trunk (sailing) and a tandem sliding seat (tech-rowing) and being in the target range of maximum boat weight of 100-120 lb. (w/o a leaded daggerboard). Worst of all it HAS to be as eye pleasing as a "PerryBoat".

Without such scantling history of such an ultra-light, Im forced to build portions of a preliminary model scale boat and simply 'break it' to see which methods of cored strake joining works best ... build the cored strakes individually (resin rich and brittle) or layup the edge overlaid strake cores in 'one shot' and then hope to hell I can stretch the FG cloth without 'wrinkling' it and screw up the visual edges of the lapstrakes strakes which are the prime visual focus of such a beautiful shear-lined boat.

What I absolutely dont want to do is build a costly and time consuming female mold, nor build a 17-18ft. 'floppy hulled' nightmare thats only useful as an expensive 'planter' in a flower garden. Looks like Im going to have do some 'modeling and breaking' to prove my concept before I become involved 'up to my eyeballs'.


Thanks again for all your suggestions and advice, much appreciated !!!!!

;-)
 

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Rich,

It sounds like you need a designer. Some of the things you are looking for are contradictory, and while it might work to just change the build method of an older design to new materials, as you mention who knows what that will result in.

The light weight plus lack of internal webbing are almost directly opposed. The advantage of ribs is they allow a thinner and lighter hull.

You might want to try out Boatdesign.net and see if any of the pros there could make a suggestion. But generally the designs are done with an eye towards the building method. Where the designs are constrained by the expected build methods. Lap strake for instance allows more freedom than a tortured ply design and this is taken into account at the drawing board stage.
 

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A while back I posted some pix of an Adirondack Guideboat I built a couple of years ago. Some of the design principles may be of use in your idea, especially the rib structure. The Guideboat is a relative of Whitehall type English designs. I laminated ribs using strips of cedar but the same thing might be possible using glass or graphite. That would be pretty cool. The rib shape (very stiff) actually does the shaping as opposed to some sort of mould frame. Maybe layup some laminated planks and then cut to fit??
 

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I think you will find that for a one off craft a composite using anything else other then okume plywood, cedar or similar light rot resistant wood with a thin glass inside and out using epoxy. It will be very light and stiff. Double the cost with a good sliding seat, and nice set of oars. You could also build your own oars out of carbon fiber. If you really want to go all out use carbon fiber or S Glass on the outside and Kevlar inside.

There is a ton of info on boat design forum, wooden boat forum, West Systems boat building book is priceless well actually free from their website. http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook 061205.pdf

It will help you understand the different construction techniques and whats involved.

Does budget matter? Do you think you will want to vacuum bag it all and have a female or male mold you precisely made. There is a ton of variation in row boats depending on desired use and most plans are very reasonably priced and designers usually offer a lot of support. Some offer kits which make it all a lot quicker. Clint Chase's Drake is pretty sweet and I think he is coming out with a kit. Good luck and have fun.
 

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The Gougeon brother's book on boat construction examines a wide range of options, including composite core materials. In the book they discuss the different materials they tested, and by my reading, determine that wood/epoxy is pretty much the best material to work with for boat building. Since you appear to want a lapstrake boat, plywood might provide the most flexibility for strakes of varying width that bend uniformly. Otherwise, cedar strip might be a viable alternative. Nick Schade, at Guillemot kayaks, has developed some pulling boat designs that are also available through Chesapeake Light Craft.
 

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Hard to beat the beauty of a wood lapstrake white hall. More difficult to find the suitable planks even here in BC, the land of giant cedars. Although I've not seen it done how about strip gluing up individual planks as if building a flat canoe. After sanding and preping, plank up the usual hull over molds .And finish bright on the outside. Probably want ribs and hardwood gunnel in the old fashioned way but what a work of art. Not reinventing the wheel either.
 

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Lapstrake Whitehalls are indeed gorgeous - there is an expensive glass one built in Victoria.

That said, I've also seen them built smooth and they are also gorgeous - and much more suitable for super lightweight cored construction.
 

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Over Hill Sailing Club
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Hard to beat the beauty of a wood lapstrake white hall. More difficult to find the suitable planks even here in BC, the land of giant cedars. Although I've not seen it done how about strip gluing up individual planks as if building a flat canoe. After sanding and preping, plank up the usual hull over molds .And finish bright on the outside. Probably want ribs and hardwood gunnel in the old fashioned way but what a work of art. Not reinventing the wheel either.
Yep. I tried to find some White Cedar a couple of years ago to no avail.
30 years ago there were barns full of it.

I have a hunch that the coefficients of expansion of the substrate materials and resins are the biggest problem to deal with in choosing composites as a core. That's why wood and West System epoxy works so well. They move with temp. about the same rate.
 

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Thanks for all the hints and advice, much appreciated and all 'food for thought'.
I already have a design in mind such as the heavyweight Wherry from John Gardner's textbook ... easy to loft from the detailed offsets already in existence (Mystic).

The execution in ultra-light composites is the 'grey area' in that there is insufficient historical scantling/strength performance data whether by molding a complete lapstraked-looking (an absolute requirement) hull versus the stress considerations of the resin rich areas that joining such strakes as individual strakes as when building in wood ..... or lay-up the strake cores over a 'male plug' together & simultaneously. Couple that with a desire for a monocoque hull (little to no ribs/knees and other internal supports, etc.), daggerboard trunk (sailing) and a tandem sliding seat (tech-rowing) and being in the target range of maximum boat weight of 100-120 lb. (w/o a leaded daggerboard). Worst of all it HAS to be as eye pleasing as a "PerryBoat".

Without such scantling history of such an ultra-light, Im forced to build portions of a preliminary model scale boat and simply 'break it' to see which methods of cored strake joining works best ... build the cored strakes individually (resin rich and brittle) or layup the edge overlaid strake cores in 'one shot' and then hope to hell I can stretch the FG cloth without 'wrinkling' it and screw up the visual edges of the lapstrakes strakes which are the prime visual focus of such a beautiful shear-lined boat.

What I absolutely dont want to do is build a costly and time consuming female mold, nor build a 17-18ft. 'floppy hulled' nightmare thats only useful as an expensive 'planter' in a flower garden. Looks like Im going to have do some 'modeling and breaking' to prove my concept before I become involved 'up to my eyeballs'.

Thanks again for all your suggestions and advice, much appreciated !!!!!

;-)
Try Dynel fabric I got it from Defender you can wrap a football wrinkle free on 1 side at least and very strong.
 
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